1. Field of the Invention
This invention relates to a display device having adjoining display elements and more particularly, to a liquid crystal display suitable for use in instrument panels.
2. Description of the Prior Art
Display elements disposed geometrically in at least one row are excellently suited for displaying analogue information, such as speed, temperature, or pressure. A known example of this kind is the mercury thermometer. In this case the length of the column of mercury is proportional to the measured variable temperature.
Electronic display devices of this kind can be produced by linear arrangement, or for example in the case of the representation of time also by circular arrangement, of individual electro-optical display elements. If a display device of this kind is to have sufficiently great resolving power, a large number of individual elements is required. If each of these individual elements is individually driven, a large number of electronic drive stages and connecting lines is required, which usually is prohibitively costly.
For this reason display devices have been developed which have display elements grouped together in matrix fashion and also with multiplex driving--see German Offenlegungsschrift No. 2,408,062.
In liquid crystal displays having no optical storage the maximum achievable contrast is limited by the transient response of the individual display elements. With multiplex drive and with a 50% pulse duty factor, display elements whose switch times are sufficiently short give a mean contrast which corresponds to half the peak contrast. Nematic liquid crystal displays, whose optical drive state follows the effective value of the drive voltage, have a very limited mean contrast which corresponds to that of static driving of the display elements at about 2.2 times the effective value of the threshold voltage.